Rod Coercer

ABSTRACT

A rod coercer for use in spinal fixation procedures is provided. The rod coercer can be pivoted in a first direction to fixedly grip an implant, and pivoted in a second direction to reduce a rod into the implant. In one embodiment, the rod coercer includes first and second articulating handle branches, first and second rod contacting arms extending from the first and second handle branches, first and second implant gripping arms pivotally interconnected with the first and second handle branches, and means for releasably locking the handle branches and the implant gripping arms in a closed and locked position. In another embodiment, the implant gripping arms of the rod coercer can be secured to each other by a flexible retainer.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/413,318 filed on Mar. 6, 2012, now U.S. Pat. No. 8,449,549, which isa continuation of U.S. patent application Ser. No. 12/692,212 filed Jan.22, 2010, now U.S. Pat. No. 8,137,357, which is a continuation-in-partof U.S. patent application Ser. No. 12/357,782 filed Jan. 22, 2009, nowU.S. Pat. No. 8,128,629, the entire disclosures of which are expresslyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to instruments for use in surgicalapplications, and more specifically, to a rod coercer for positioning arod into a surgical implant during a spinal fixation procedure.

2. Related Art

In spinal fixation surgery, a rod and a set of vertebral implants (e.g.,pedicle screws) are often used to correct spinal deformities. In suchprocedures, the rod is often bent to a desired shape using anappropriate rod bender. Then, a surgeon installs the implants inselected vertebral bodies along the length of the spine. Each implantusually includes a head which is shaped to receive a portion of the rod.After the implants have been installed, the rod is seated or “reduced”into the head of an implant, using a device which applies force to therod and the implant, so that the implant and its associated vertebralbody, and the rod, are drawn together, and a portion of the rod isseated in the head of the implant. Once the rod has been reduced intothe head of the implant, a cap is engaged with (e.g., threaded into) thehead of the implant and tightened to retain the rod in the head of theimplant. This process may be repeated for each of the remainingimplants, as needed, until the rod has been reduced into all of theimplants. Once the procedure is complete, the spine conforms to theshape of the rod, to correct the spinal deformity. Thus, it is veryimportant in such procedures to properly reduce a spinal rod into itsassociated implants.

Various devices for reducing a rod into an implant are known. Oneexample is a simple forceps-type apparatus which includes articulatingforceps branches and a bifurcated gripping nose which pivotally gripsthe head of an implant. When the forceps branches are closed and thepivotal grip is established, the device can be pivoted with respect tothe implant to contact a rod and to exert force on same using a fulcrumarrangement, so as to reduce the rod into the head of the implant. Otherdevices include rod reducers having axially-aligned, concentric sleevesthat move axially with respect to each other. Such devices include apistol and trigger grip, as well as a ratchet mechanism interconnectedwith the trigger to urge one of the sleeves axially relative to anothersleeve, causing prongs of the inner sleeve to grip an implant and theouter sleeve to reduce the rod into the implant. Another device includesa forceps-type instrument which grips an implant, and a separatearticulating device which attaches to the forceps-type instrument andwhich pivots to reduce a rod into the implant.

SUMMARY OF THE INVENTION

The present invention relates to a rod coercer for use in spinalfixation procedures. The rod coercer includes first and secondarticulating forceps branches, first and second rod contacting armsextending from the first and second forceps branches, and first andsecond implant gripping arms pivotally interconnected with the first andsecond forceps branches. The forceps branches can be pivoted away fromeach other to open the implant gripping arms so that the arms can bepositioned about the head of an implant and a rod to be reduced into theimplant. The forceps branches can then be pivoted toward each other toclamp the implant gripping arms against the head of the implant, suchthat the head of the implant is fixedly gripped by the implant grippingarms. Optionally, corresponding locking tabs could be provided on theforceps branches for retaining the forceps branches and the implantgripping arms in a closed and locked position. After clamping theimplant with the implant gripping arms, the forceps branches can bepivoted about the implant gripping arms so that the rod contacting armscontact the rod and the implant gripping arms draw the implant and therod toward each other to reduce the rod into the head of the implant.

In another embodiment of the present invention, the rod coercer includespivotally interconnected forceps branches, each of which is divided intoupper and lower branch portions which are pivotally interconnected witheach other so that the upper branch portion can be pivoted with respectto the lower branch portion. First and second implant gripping armsextend from the lower branch portions of the forceps branches. A rodcontacting arm is provided, and is interconnected to an upper branchportion of one of the forceps branches by an upper linkage, and to alower branch portion of the same forceps branch by a lower linkage. Theforceps branches can be pivoted away from each other to open the implantgripping arms so that the arms can be positioned about the head of animplant and a rod to be reduced into the implant. The forceps branchescan then be pivoted toward each other to clamp the implant gripping armsagainst the head of the implant, such that the head of the implant isfixedly engaged by the implant gripping arms. Optionally, correspondinglocking tabs could be provided on the forceps branches for retaining theforceps branches and the implant gripping arms in a closed and lockedposition. After clamping the implant with the implant gripping arms, theupper branch portions can be pivoted with respect to the lower branchportions, so that the rod contacting arm contacts a rod and the implantgripping arms draw the implant and the rod together to reduce the rodinto the head of the implant.

In another embodiment of the present invention, the forceps branchesinclude first and second implant gripping arms which are pivotallyinterconnected with the branches, and a rod contacting arm coupled bygears to one of the forceps branches. An end of one of the forcepsbranches is attached to the face of a forceps gear, and an end of therod contacting arm is attached to the face of an arm gear, such that thearm gear meshes with the forceps gear. The forceps branches can bepivoted away from each other to open the implant gripping arms so thatthe arms can be positioned about the head of an implant and a rod to bereduced into the implant. The forceps branches can then be pivotedtoward each other to clamp the implant gripping arms against the head ofthe implant, such that the head of the implant is fixedly gripped by theimplant gripping arms. Optionally, corresponding locking tabs could beprovided on the forceps branches for retaining the forceps branches andthe implant gripping arms in a closed and locked position. Afterclamping the implant with the implant gripping arms, the forcepsbranches can be pivoted with respect to the implant gripping arms, sothat the forceps gear rotates the arm gear to pivot the rod contactingarm downwardly to contact the rod and the implant gripping arms draw theimplant toward the rod to reduce the rod into the head of the implant.

In another embodiment of the present invention, the rod coercer includesfirst and second articulating handle branches, first and second rodcontacting arms extending from the first and second handle branches, andfirst and second implant gripping arms pivotally interconnected with thefirst and second handle branches. The handle branches can be pivotedaway from each other to open the implant gripping arms so that the armscan be positioned about the head of an implant and a rod to be reducedinto the implant. The handle branches can then be pivoted toward eachother to clamp the implant gripping arms against the head of theimplant, such that the head of the implant is fixedly gripped by theimplant gripping arms. Means for releasably locking the handle branchesare provided for retaining the handle branches and the implant grippingarms in a closed and locked position. The means for releasably lockingcould include a ratcheting assembly having a hinged, toothed leverextending from one handle branch to engage an angled pawl on the secondhandle branch. After clamping the implant with the implant grippingarms, the handle branches can be pivoted about the implant gripping armsso that the rod contacting arms contact the rod and the implant grippingarms draw the implant and the rod toward each other to reduce the rodinto the head of the implant.

In another embodiment of the present invention, the rod coercer includesa single handle having first and second implant gripping arms connectedby a bridge and pivotally attached to the handle. Each implant grippingarm includes a spring-loaded locking lever for gripping sides of animplant. Springs bias protrusions on ends of the locking levers so thatthe protrusions extend through apertures in the implant gripping armsand into corresponding recesses in the implant to fixedly engage theimplant. The levers can be pressed inward to disengage the protrusionsfrom the recesses of the implant, to allow for removal of the rodcoercer from the implant. Optionally, the levers can be L-shaped. Afterfixedly engaging the implant with the spring-loaded locking mechanismand implant gripping arms, the handle can be pivoted with respect to theimplant gripping arms, so that the rod contacting arm contacts a rod andthe implant gripping arms draw the implant and the rod together toreduce the rod into the head of the implant.

In another embodiment of the present invention, the rod coercer includesan adjustable rod contacting arm which can be adjusted to a desiredangle with respect to the handles of the coercer. An implant grippingarm assembly (e.g., two implant gripping arms) is provided at ends ofthe handles, is pivotally connected thereto, and is positionable aboutthe head of an implant and secured thereto. The rod contacting arm canthen by adjusted to the desired angle using an adjustment assemblyassociated with the rod contacting arm. The adjustment assembly couldinclude a screw, or threaded shaft, pivotally attached at one end to thehandle and extending through a threaded aperture of the rod contactingarm. The adjustment assembly could also include a partial gear attachedto the handle and in mechanical communication with a worm gearpositioned within the rod contacting arm. Rotation of the worm gear, bya key or other device, alters the angle of the rod contacting arm. Whenthe rod contacting arm is positioned at a desired angle, the handles canthen be pivoted with respect to the implant gripping arms, so that thehandle pivots the rod contacting arm downwardly to contact the rod andthe implant gripping arms draw the implant toward the rod to reduce therod into the head of the implant.

In another embodiment of the present invention, the rod coercer includespivotally interconnected handle branches, each of which is divided intoupper and lower branch portions which are pivotally interconnected witheach other so that the upper branch portion can be pivoted with respectto the lower branch portion, an implant gripping assembly extending fromthe lower branch portions of the handle branches, and a rod contactingarm slidably and pivotally coupled to the upper branch portion by afirst joint and slidably coupled to the lower branch by a second joint.The handle branches can be pivoted away from each other to open theimplant griping arms so that the arms can be positioned about the headof an implant and a rod to be reduced into the implant. The handlebranches can then be pivoted toward each other to clamp the implantgripping arms of the implant gripping assembly against the head of theimplant, such that the head of the implant is fixedly engaged by theimplant gripping arms. After engaging the implant with the implantgripping assembly, the upper branch portions can be pivoted with respectto the lower branch portions, causing the rod contacting arm to contacta rod and the implant gripping arms to draw the implant and the rodtogether to reduce the rod into the head of the implant.

In another embodiment of the present invention, the implant grippingarms of the rod coercer of the present invention are secured to eachother by a flexible retainer. Pivoting the arms towards each othercauses the flexible retainer to flex upwardly so that the implant may begripped properly without interference from arch. Urging the grippingarms away from each other causes the retainer to flex.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention will be apparent from thefollowing Detailed Description of the Invention, taken in connectionwith the accompanying drawings, in which:

FIG. 1 is a perspective view showing the rod coercer of the presentinvention;

FIG. 2 is a partial perspective view showing the rod coercer of FIG. 1in greater detail;

FIG. 3 is a partial front view showing the rod coercer of FIG. 1 ingreater detail;

FIGS. 4A-4C are side views showing operation of the rod coercer of FIG.1 to reduce a surgical rod into the head of an implant;

FIGS. 5A-5C are rear and side views of another embodiment of the rodcoercer of the present invention, which includes pivotable upper andlower forceps branches and a rod contacting arm interconnectedtherewith;

FIGS. 6A-6C are partial rear, perspective, and side views of anotherembodiment of the rod coercer of the present invention, which includespivotable implant gripping arms and a geared rod contacting arm;

FIG. 7 is a perspective view showing another embodiment of the rodcoercer of the present invention, wherein integral rollers are providedat ends of the rod contacting arms and a retainer interconnects theimplant gripping arms to maintain the arms in facing relationship;

FIG. 8 is a perspective view of a cannula that can be used with the rodcoercer of the present invention;

FIG. 9 is a perspective view showing the rod coercer of the presentinvention, wherein releasable locking means are provided on the handlesof the rod coercer;

FIGS. 10A-11D are perspective, side, and cross-sectional views showinganother embodiment of the rod coercer of the present invention whichincludes a single handle and spring-loaded implant gripping levers forreleasably locking the rod coercer to an implant;

FIGS. 12A-13B are side and cross-sectional views of another embodimentof the rod coercer of the present invention in greater detail, whereinan adjustable rod contacting arm assembly is provided;

FIGS. 14A-14B are side views showing another embodiment of the rodcoercer of the present invention, which includes pivotable upper andlower forceps branches and a rod contacting arm slidably coupledtherewith by first and second slidable joints; and

FIGS. 15A-15C are partial perspective and front views showing anotherembodiment of the rod coercer of the present invention in greaterdetail, wherein a flexible retainer interconnects the implant grippingarms to maintain the arms in facing relationship.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a rod coercer for use in spinalfixation procedures. The rod coercer includes handle branches which canbe pivoted along a first arc (i.e., about a first axis) to fixedly gripthe head of an implant, and which can be pivoted along a second arc(i.e., about a second axis) to reduce a rod into the head of theimplant. By the terms “coerce” and “reduce,” it is meant the seating ofa rod into a surgical implant through a mechanical application of force,such that the implant and the rod are drawn together and the rod isseated into the head of the implant.

FIG. 1 is a perspective view showing the rod coercer 10 of the presentinvention. The rod coercer 10 includes right and left forceps branches12, 14 which are pivotally interconnected at a pivot point 16 (e.g., bya pin extending through and pivotally interconnecting the branches 12,14, or any other suitable type of pivotable interconnection). Thebranches 12, 14 include finger loops 18, 20 for receiving an operator'sfingers. Optionally, corresponding locking tabs 22 (which includedmating inner surfaces having teeth) could be provided for maintainingthe branches 12, 14 in a closed and locked arrangement. Rod contactingarms 24, 26, which contact a rod to reduce it into an implant, areprovided at the ends of the branches 12, 14. Implant gripping arms 28,30 are pivotally interconnected with the branches 12, 14. The implantgripping arms 28, 30 fixedly grip an implant 50 (which could be a screw(e.g., pedicle screw), hook, or any other suitable implant which isconfigured to receive a rod), while the arms 24, 26 pivot with respectto the arms 28, 30 to reduce a rod into the implant 50.

To grip the implant 50, the forceps branches 12, 14 are pivoted awayfrom each other about a first axis (in the direction shown by arrow A),which causes both the implant gripping arm 28 to move away from theimplant gripping arm 30, and consequently, the arms 24, 26 similarlymove away from each other. The arms 28, 30 are then positioned aboutopposite sides of the implant 50, as well as about a rod (not shown inFIG. 1) to be reduced into the implant 50. The forceps branches 12, 14are then urged toward each other in the direction shown by arrow A, byan operator's fingers applying force to the branches 12, 14, so that thearms 28, 30 fixedly clamp the implant 50 and, consequently, the arms 24,26 are brought together. The arms 28, 30 each have inner surfaces whichcould be cylindrical in shape or could have any other shape configuredto match the shape of the implant 50. The inner surfaces contact thesides of the implant 50 and are held in a fixed position against theimplant 50 when the arms 28, 30 are clamped against the implant 50. Thelocking tabs 22, if provided, maintains the forceps branches 12, 14 andthe arms 28, 30 in a locked configuration, such that the arms 28, 30remain clamped against the implant 50 when the operator releases his orher grip on the rod coercer 10. Advantageously, this frees the surgeon'shand to perform other tasks (if desired or necessary) prior to reductionof a rod, as discussed below. When the arms 28, 30 are clamped againstthe implant 50, the forceps branches 12, 14 can pivot with respect tothe arms 28, 30, in the direction shown by arrow B. As discussed below,this motion allows for reduction of a rod into the implant 50. Thus, therod coercer 10 can be pivoted in a first direction (i.e., about a firstaxis) to fixedly grip the implant 50, and can be pivoted in a seconddirection (i.e., about a second axis) generally transverse to the firstdirection to reduce a rod into the implant 50.

FIG. 2 is a partial perspective view showing the rod coercer 10 ingreater detail. As mentioned above, the arms 28, 30 are pivotallyinterconnected with the branches 12, 14. Such a pivotableinterconnection could be provided by a first pin 32 inserted through thearm 30 and the branch 12, and a second pin 34 inserted through the arm28 and the branch 14, as well as any other suitable type of pivotableinterconnection between the arms 28, 30 and the branches 12, 14, such asscrews having smooth (pin-like) portions on the shafts thereof aboutwhich the arms 28, rotate. The arms 28, 30 clamp opposite sides of thehead 52 of the implant 50, and optionally include shoulders 36, 38. Thespace between the arms 28, 30 allows for insertion of a threaded cap,which could be threaded into the head 52 of the implant 50 to lock a rodto the implant 50, as well as an instrument for tightening such a cap.

FIG. 3 is a partial front view showing the rod coercer 10 in greaterdetail. The arms 24, 26 could include curved surfaces 40, 42 which couldbe shaped to receive the rod. This facilitates a proper interfacebetween the arms 24, 26 as they bear against a rod during reduction ofthe rod into the implant 50. The shape of the curved surfaces 40, 42could be varied to accommodate the geometry of the rod. It is noted thatthe arms 24, 26 need not extend at an angle to the branches 12, 14.Indeed, the arms 24, 26 could be parallel to the branches 12, 14.Additionally, the shapes and angles of the arms 24, 26 could be modifiedso that the arms 24, 26 can contact the rod at any desired location. Itis also noted that a single arm could be provided for contacting the rodto reduce it into an implant.

The shoulders 36, 38, if provided, abut opposed upright walls 54, 56 ofthe head 52 of the implant 50 when the arms 28, 30 are clamped againstthe walls 54, 56 of the head 52. The shoulders 36, 38 help to preventthe rod coercer 10 from moving with respect to the implant 50 when thehead 52 is clamped by the arms 28, 30. It is noted that the arms 28, 30and walls 54, 56 could include complementary mechanical engagements(e.g., in the form of protrusions and corresponding recesses, etc.)which prevent movement between the arms 28, 30 and the implant 50 whenthe head 52 is clamped by the arms 28, 30. Such a protrusion is shown inFIG. 6B, discussed below, and could be provided in any desired geometry.The walls 54, 56 define a channel 58 into which a surgical rod isreduced by the arms 24, 26.

FIGS. 4A-4C are side views showing operation of the rod coercer 10 toreduce a surgical rod 60 into the head 52 of the rod 50. First, as shownin FIG. 4A, the arms 28, 30 of the rod coercer 10 are clamped againstthe head 52 of the implant 50 in the manner discussed above, such thatthe rod 60 is positioned between the arms 28, 30 and the arms 24, 26 arepositioned above the rod 60. As can be seen, the implant gripping arms28, 30 and the rod contacting arms 24, 26 define a first angle withrespect to each other. Then, as shown in FIG. 4B, the forceps branches12, 14 are pivoted in the direction shown by arrow B. This causes thearms 24, 26 to move downwardly in the direction shown by arrow C, sothat the arms 24, 26 contact and exert force against the rod 60. As canbe seen, when the branches 12, 14 are pivoted, a second angle (differentthan the first angle shown in FIG. 4A) is defined between the implantgripping arms 28, 30 and the rod contacting arms 24, 26. The implant 50(and an anatomical structure, such as a vertebral body, in which theimplant 50 is installed) is then moved upwardly toward the rod 60, asshown by arrow D. It is noted that the rod 60 could also be moveddownwardly toward the implant 50, i.e., in a direction opposite thedirection shown by arrow D. Thus, the arms 24, 26 operate as levers formoving the implant 50. Finally, as shown in FIG. 4C, the branches 12, 14are further pivoted in the direction of arrow B, so that the arms 24, 26are urged to a final position against the rod 60. In this position, therod 60 is reduced into the head 52 of the implant 50, and a threaded capor other type of locking device can be installed into the head 52 of theimplant 50 to lock the rod 60 in position in the head 52. Once the rodis locked with respect to the implant 50 using a suitable lockingdevice, the rod coercer 10 can be removed from the implant 50 bypivoting the forceps branches 12, 14 away from each other.

FIGS. 5A-5C are rear and side views of another embodiment of the rodcoercer of the present invention, indicated generally at 100. The rodcoercer 100 includes forceps branches 112, 114 which are pivotallyinterconnected and which can be pivoted with respect to each other, inthe direction shown by arrow E. The branch 112 is divided into upper andlower branch portions 112 a, 112 b which pivot with respect to eachother, and the branch 114 is divided into upper and lower branchportions 114 a, 114 b which pivot with respect to each other. Implantgripping arms 128, 130 are provided at the ends of the lower branchportions 112 b, 114 b for gripping opposite sides of the head 52 of theimplant 50, and finger loops 118, 120 are provided at opposite ends ofthe branches 112, 114 for receiving an operator's fingers. The grippingarms 128, 130 can be brought together to clamp the head 52 of theimplant 50 by urging the branches 112, 114 together in the direction ofarrow E. Corresponding locking tabs 122 could be provided to lock thebranches 112, 114 together, which locks the gripping arms 128, 130against the head 52 of the implant 50. Upper and lower linkages 132 a,132 b link a rod contacting arm 124 to the upper and lower branchportions 114 a, 114 b of the forceps branch 114. Of course, the linkages132 a, 132 b could be attached to the upper and lower branch portions112 a, 112 b of the forceps branch 112.

As shown in FIG. 5B, an upper end of the rod contacting arm 124 ispivotally interconnected to the upper branch portion 114 a by thelinkage 132 a, such that the linkage 132 a is fixedly attached at oneend to the upper branch portion 114 a and pivotally attached at anopposite end to the rod contacting arm 124. The lower end of the rodcontacting arm 124 is linked to the lower branch portion 114 b by thelinkage 132 b, such that the linkage 132 b is pivotally attached at oneend to the lower branch portion 114 b and pivotally attached at anopposite end to the rod contacting arm 124. A curved surface 134 couldbe provided at the bottom of the rod contacting arm 124, which could beshaped to match the shape of the rod 60.

The upper and lower branch portions 112 a, 114 a and 112 b, 114 b arepivotally interconnected by a pivotable interconnection 136 provided ineach branch 112, 114, which allows the upper branch portions 112 a, 114a to pivot with respect to the lower branch portions 112 b, 114 b, asshown by arrow F in FIG. 5C. Such movement causes the rod contacting arm124 to move downwardly in the general direction indicated by arrow G, sothat the rod contacting arm 124 contacts the rod 60. This causes theimplant 50 (and an anatomical structure in which it is installed, suchas a vertebral body) to be drawn upwardly toward the rod 60, so as toreduce the rod 60 into the head 52 of the implant 50. It is also notedthat the rod contacting arm could cause the rod 60 to move downwardlytoward the implant 50 to reduce the rod 60 into the head 52 of theimplant 50.

FIGS. 6A-6C are partial rear, perspective, and side views of anotherembodiment of the rod coercer of the present invention, indicatedgenerally at 200. As shown in FIG. 6A, the rod coercer 200 includesbranches 212, 214 which are pivotally interconnected via pivotableinterconnection 216 and which can be pivoted with respect to each other,in the direction of arrow H. Upper ends of the branches 212, 214 couldinclude finger loops and, optionally, locking tabs, such as the fingerloops and locking tabs shown in the previous embodiments. Implantgripping arms 226, 228 are provided for gripping opposite sides of thehead 52 of the implant 50, and can be brought together to clamp the head52 of the implant 50 by urging the branches 212, 214 together in thedirection of arrow H.

As shown in FIG. 6B, the implant gripping arms 226, 228 are pivotallyinterconnected with the branches 212, 214 via joints 230, 232. The joint230 is formed by a collar 250 attached to an end of the branch 212,which pivots about a pin 252 extending through the upper portion of thegripping arm 226. The joint 232 links a rod contacting arm 234 to theforceps branch 214. The branch 214 is attached to a face of a forcepsgear 242, and the rod contacting arm 234 is attached to the face of anarm gear 240, both of which gears 240, 242 intermesh. The gears 240, 242rotate about pins 244, 246 inserted into an upper end of the implantgripping arm 228. Thus, both the forceps branch 214 and the rodcontacting arm 234 pivot at adjacent pivot points in joint 232.

Optionally, protrusions 248 could be provided on the rod contacting arms226, 228 for insertion into corresponding recesses formed on an implant.The geometry of such protrusions could be varied as desired. Also, therod contacting arm 234 could be bent (as shown in FIG. 6B) or providedin any desired shape or geometry. Additionally, a curved surface 236,shaped to match the shape of a rod, could be provided on the rodcontacting arm 234.

As shown in FIG. 6C, when the branches 212, 214 are pivoted in thedirection of arrow I, the forceps gear 242 rotates. This causes the armgear 240 to rotate, which causes the rod contacting arm 234 to pivot inthe direction of arrow J, so that the surface 236 contacts the rod 60.This causes the implant 50 (and an anatomical structure (e.g., avertebral body) into which the implant 50 is installed) to be drawnupwardly toward rod 60 by the implant gripping arms 228, 230, asindicated by arrow K, so that the rod is reduced into the head 52 of thescrew 50. It is noted that the rod 60 could also be urged downwardlytoward the screw 50 to reduce the rod 60 into the head 52 of the screw50.

FIG. 7 is a perspective view showing another embodiment of the presentinvention, which is similar in construction to the rod coercer shown inFIGS. 1-4C. In this embodiment, integral rollers 352, 354 are providedon ends of the rod contacting arms 324, 326, which roll along a rod asit is reduced. The rollers 352, 354 reduce friction between the rod andthe arms 324, 326, thereby reducing the amount of force required toreduce a rod. Also provided is a flexible retainer 356 interconnectingthe implant gripping arms 328, 330. The retainer 356 allows the arms328, 330 to be maintained in facing relationship with each other as theyare pivoted with respect to forceps branches 312, 314. Also, theretainer 356 stretches (as shown by arrow L) so that the arms 328, 330can be spread apart by manipulating the forceps branches 312, 314. Assuch, the retainer 356 does not interfere with operation of the rodcoercer. The rollers 352, 354 could be provided on the rod contactingarms of each of the embodiments of the rod coercer disclosed herein, andthe flexible member 356 could be provided for interconnecting theimplant gripping arms of each embodiment of the rod coercer disclosedherein.

FIG. 8 is a perspective view showing a cannula (guide tube) 400 whichcould be utilized with each embodiment of the rod coercer of the presentinvention. The cannula 400 could be positioned between the implantgripping arms of the present invention to guide a set screw and anassociated tightening tool for locking a rod into an implant. The shapeand size of the cannula 400 could be modified as desired withoutdeparting from the spirit or scope of the present invention. It is alsonoted that the cannula 400 could be threadably, frictionally, orotherwise engaged with the implant gripping arms of the presentinvention (e.g., using corresponding interlocking protrusions/recessesto lock the cannula 400 to the arms).

FIG. 9 is a perspective view showing another embodiment of the rodcoercer of the present invention, indicated generally at 500. The rodcoercer 500 includes right and left handle branches 512, 514 which arepivotally interconnected at a point 516 (e.g., by a pin extendingthrough and pivotally interconnecting the branches 512, 514, or anyother suitable type of pivotable interconnection). The branches 512, 514include means for releasably locking the branches 512, 514 in a closedand locked position, such as a ratchet mechanism comprising a pivotabletoothed lever 522 rotating about a hinge 525 on one handle and a pawl523 located on the opposite handle. Rod contacting arms 524, 526, whichcontact a rod to reduce it into an implant, are provided at the ends ofthe branches 512, 514. Implant gripping arms 528, 530 are pivotallyinterconnected with the branches 512, 514. The implant gripping arms528, 530 fixedly grip an implant 50 (which could be a screw (e.g.,pedicle screw), hook, or any other suitable implant which is configuredto receive a rod), while the rod contacting arms 524, 526 pivot withrespect to the implant gripping arms 528, 530 to reduce a rod into theimplant 50.

To grip the implant 50, the handle branches 512, 514 are pivoted awayfrom each other about a first axis (in the direction shown by arrow M),which causes the implant gripping arm 528 to move away from the implantgripping arm 530, and consequently, the arms 524, 526 similarly moveaway from each other. The arms 528, 530 are then positioned aboutopposite sides of the implant 50, as well as about a rod (not shown inFIG. 9) to be reduced into the implant 50. The handle branches 512, 514are then urged toward each other in the direction shown by arrow M, byan operator's hand applying force to the branches 512, 514, so that thearms 528, 530 fixedly clamp the implant 50 and, consequently, the arms524, 526 are brought together. The gripping arms 528, 530 each haveinner surfaces which could be cylindrical in shape or could have anyother shape configured to grip or hold the implant 50. The innersurfaces contact the sides of the implant 50 and are held in a fixedposition against the implant 50 when the arms 528, 530 are clampedagainst the implant 50. When the arms 528, 530 are clamped against theimplant 50, the handle branches 512, 514 can pivot with respect to thearms 528, 530, in the direction shown by arrow N. As discussed herein,this motion (similar to the motion shown by arrow B in FIGS. 1 and4B-4C) allows for reduction of a rod into the implant 50.

To utilize the ratchet mechanism, as the branches 512, 514 are urgedtogether, the pawl 523 moves with respect to the teeth of the lever 522until the branches 512, 514 stop moving and the pawl 523 settles againstone of the teeth of the lever 522. The teeth of the lever 522 are shapedsuch that after the branches 512, 514 are urged together, the teethretain the pawl 523 in a fixed position, thereby locking the branches512, 514 together. This locks of the handles 512, 514 in position as theimplant gripping arms 528, 530 hold the implant 50. The coercer 500 canbe released from the implant 50 by pivoting the lever 522 upwardly, sothat the pawl 523 disengages from the lever 522.

It is noted that the ratchet mechanism shown in FIG. 9 could besubstituted with any other suitable means for releasably locking thehandle branches 512, 514, such as a screw that releasably locks thehandle branches 512, 514, or any other suitable type of interconnection.

FIGS. 10A-11D are perspective, side, and cross-sectional views showinganother embodiment of the rod coercer of the present invention,indicated generally at 600, having a single handle 612 and spring-loadedimplant gripping levers 631, 633. As shown in FIGS. 10A-10B, the rodcoercer 600 includes a single handle 612 which is pivotallyinterconnected with an implant gripping assembly 620 at a pivot point614 via a pin 616, allowing the assembly 620 to be pivoted in thedirection shown by arrow O. One end of the handle 612 includes a rodcontacting arm 624 and a curved rod-contacting surface 626.Spring-loaded implant gripping levers 631, 633 are provided on implantgripping arms 628, 630, which are attached to extension arms 618, 622.The gripping arms 628, 630 are affixed to each other by a bridge 620which connects the extension arms 618, 622.

As shown in FIG. 10C, the spring-loaded locking levers 631, 633 areconnected to the implant gripping arms 628, 630 by hinges 636, 638.Springs 644, 646 bias upper ends 632, 634 of the levers 631, 633 awayfrom the arms 628, 630, forcing projections 640, 642 through apertures648, 650 in the arms 628, 630, and causing the projections 640, 642 toengage recesses 51 in the head 52 of the implant 50 to lock the arms628, 630 in position on sides of the implant 50. To engage the arms 628,630 with the implant 50, the upper ends 632, 634 of the locking levers631, 633 are first pressed in the direction shown by arrows Q. Thiscauses the protrusions 640, 642 to retract from the apertures 648, 650,as shown by arrows R. Then, the arms 628, 630 are positioned about thehead 52 of the implant 50, and the implant gripping levers 632, 634 arereleased by the operator. The springs 646, 648 urge the protrusions 640,642 through the apertures 648, 650 and into the recesses 51, therebyfixedly engaging the arms 628, 630 (and, thus, the rod coercer 600) tothe implant 50. To disengage the coercer 600 from the implant 50 (afterrod reduction), the upper ends 632, 634 of the levers 631, 633 aredepressed, resulting in the disengagement of the projections 640, 642from the recesses 51 in the direction shown by arrows R. Optionally, theprotrusions 640, 642 may be angled or rounded so that the implantgripping arms 628, 630 can be pushed directly on to the implant head 52to obviate the need to depress the upper ends 632, 634.

Optionally, the spring-loaded implant gripping levers can be L-shaped,as shown in FIGS. 11A-D. As shown therein, the rod coercer 600 includesa single handle 712 which is pivotally interconnected with an implantgripping assembly 720 at a pivot point 714 via a pin 716, allowing theassembly 720 to be pivoted in the direction shown by arrow S. One end ofthe handle 712 includes a rod contacting arm 724 and a curvedrod-contacting surface 726. L-shaped, spring-loaded implant grippinglevers 731, 733 are provided on implant gripping arms 728, 730, whichare attached to extension arms 718, 722. The gripping arms 728, 730 areaffixed to each other by a bridge 720 which connects the extension arms718, 722.

As shown in FIG. 11D, the spring-loaded locking levers 731, 733 areinterconnected to the implant gripping arms 728, 730 by hinges 778, 779.Springs 780, 782 bias ends 784, 786 of the levers 731, 733 away from thearms 728, 730, forcing projections 770, 774 through apertures 772, 776in the arms 728, 730, and causing the projections 770, 774 to engagerecesses in the head of an implant (see, e.g., implant 50 discussedabove) to lock the arms 728, 730 in position on sides of the implant. Toengage the arms 728, 730 with the implant, the ends 784, 786 of thelevers 731, 733 are first pressed in the direction shown by arrows T.This causes the protrusions 770, 774 to retract from the apertures 772,776, as shown by arrows U. Then, the arms 728, 730 are positioned aboutthe head of the implant, and the ends 784, 786 of the implant grippinglevers 731, 733 are released by the operator. The springs 780, 782 urgethe protrusions 770, 774 through the apertures 772, 776 and into therecesses, thereby fixedly engaging the arms 728, 730 (and, thus, the rodcoercer 600) to the implant 50. To disengage the coercer 600 from theimplant 50 (after rod reduction), the ends 784, 786 of the levers 731,733 are depressed, resulting in the disengagement of the protrusions770, 774 from the recesses in the direction shown by arrows U.Optionally, the protrusions 770, 774 may be angled or rounded so thatthe implant gripping arms 728, 730 can be pushed directly on to theimplant head to obviate the need to depress the ends 784, 786.

FIGS. 12A-12B are side views of another embodiment of the rod coercer ofthe present invention, indicated generally at 800, which includes a rodcontacting arm having an adjustable angle with respect to a handle. Therod coercer 800 includes a handle 812 which is pivotally interconnectedwith an implant gripping assembly 828 at a pivot point 816 and can bepivoted in the direction shown by arrow W. The implant gripping assembly828 could include any of the implant gripping arm configurations (andassociated levers, protrusions, hinges, etc.) disclosed herein, or itcould even include a single, cylindrical sleeve with internal,spring-loaded protrusions which permit the assembly 828 to be pushedonto the head of the screw 50 and releasably coupled thereto. Located onhandle 812 are two more pivot points 834, 838. The first pivot point 834is connected to a linkage 844 and associated knob 830. The knob 830includes a threaded shaft 832 and a terminal end 842 rotatably capturedwithin the linkage 844. The threaded shaft 832 is threadably engagedwith a threaded aperture 840 in an upper portion 836 of rod contactingarm 824. The second pivot point 838 is connected to the rod contactingarm 824, which includes a curved surface 826 to accommodate the geometryof a rod to be reduced.

As shown in FIG. 12B, the threaded shaft 832 remains in permanentmechanical communication with threaded orifice 840 of the adjustment arm836. Rotation of the knob 830 (as shown by arrow X in FIG. 12A) causesmechanical interaction between the threaded shaft 832 and the threadedorifice 840, resulting in movement of the upper portion 836 of the rodcontacting arm 824 along the threaded shaft 832, as shown by arrow Y ofFIG. 12A. This movement can be in either direction, depending onclockwise or counter-clockwise rotation of the knob 830. This movementresults in movement of rod contacting arm 824, along the direction shownby arrow V of FIG. 12A. Such movement allows the rod contacting arm 824to be adjusted to a desired location and angle, whereupon the handle 812can then be rotated downward in the general direction indicated by arrowW to bring rod contacting arm 824 in contact with the rod 60. Thiscauses the implant 50 and the rod 60 to be drawn together, so as toreduce the rod 60 into the head 52 of the implant 50. It is also notedthat the rod contacting arm could cause the rod 60 to move downwardlytoward the implant 50 to reduce the rod 60 into the head 52 of theimplant 50.

FIGS. 13A-13B are side views of another embodiment of the rod coercer ofthe present invention in greater detail, indicated generally at 900,which includes an adjustable rod contacting arm. The rod coercer 900includes a handle 912 which is pivotally interconnected with an implantgripping assembly 928 at a pivot point 916 and can be pivoted in thedirection shown by arrow Z. Located on the handle 912 is a second pivotpoint 938. The second pivot point 938 allows for the rotation of theadjustable rod contacting arm 924 in the general direction show by arrowAA through a fixed partial gear 940 and a worm gear 944.

The angle of the adjustable rod contacting arm 924 can be adjusted byrotating a worm gear 944 provided in the rod contacting arm 924, asshown in FIG. 13B. The partial gear 940 includes teeth 942 in mechanicalcommunication with helical grooves of the worm gear 944 of thecontacting arm 924. The worm gear 944 is connected to the contacting arm924 by a spindle 946 which allows for rotation of the gear. Of course,any other suitable way of capturing the gear 944 within the rodcontacting arm 924 could be provided. Rotation of the gear 944 isachieved using a key 952 which can be inserted through an aperture 950of the contacting arm 924 and turned. This causes the grooves of theworm gear to move along the teeth of the fixed gear 940, resulting inthe movement of the rod contacting arm 924 along the fixed gear 940, asshown by arrow AA. This allows the arm 924 to be moved to a desiredangle, whereupon the handle 912 can then be rotated downward, in thegeneral direction indicated by arrow Z, to bring the rod contacting arm924 in contact with the rod 60. This causes the implant 50 and the rod60 to be drawn together, so as to reduce the rod 60 into the head 52 ofthe implant 50.

FIGS. 14A-14B are side views showing operation of another embodiment ofthe rod coercer of the present invention in greater detail, indicatedgenerally at 1000, which includes a rod contacting arm slidably coupledto the coercer by first and second joints. The rod coercer 1000 includesupper handle branches 1012 a, 1014 a which are pivotally interconnectedwith lower handle branches 1012 b, 1014 b by pivotable interconnections1036. An implant gripping assembly 1028 is provided at the ends of thelower handle branches 1012 b, 1014 b for gripping the head 52 of theimplant 50. First and second joints 1032, 1046 interconnect arm 1024 tothe upper and lower branch portions 1014 a, 1014 b, and allow the arm1024 to slide. Of course, the joints 1032, 1046 could be attached to theupper and lower branch portions 1012 a, 1012 b. The arrangement of theupper and lower branch portions is similar to the upper and lower branchportions discussed above in connection with FIGS. 5A-5C.

As shown in FIG. 14A, the joint 1032 includes a bracket 1034 attached toone end of the upper branch portion 1014 a. The bracket 1034 includes apin 1035 which travels along a slot 1032 formed at an upper end of therod contacting arm 1024, and allows for translation and pivoting of thebracket 1034 and pin 1035 with respect to the slot 1033. The lower endof the rod contacting arm 1024 is linked to the lower branch portion1014 b by the joint 1046. The joint 1046 includes a projection 1046which is attached to, or formed with, the lower branch portion 1014 b,and which includes an aperture 1038 for receiving the contacting arm1024. The rod contacting arm 1024 translates upwardly and downwardlywithin the aperture 1038, thereby allowing for slidable coupling of thearm 1024 and the branch 1012 b. A curved surface 1026 could be providedat the bottom of the rod contacting arm 1024, which could be shaped toaccommodate the rod 60.

As mentioned above, the upper and lower branch portions 1012 a, 1014 aand 1012 b, 1014 b are pivotally interconnected by a pivotableinterconnection 1036. This allows the upper branch portions 1012 a, 1014a to pivot with respect to the lower branch portions 1012 b, 1014 b, asshown by arrow BB in FIG. 14B. Such movement causes the bracket 1034 andpin 1035 to move along the slot 1033, resulting in the movement of rodcontacting arm 1024 downwardly in the general direction indicated byarrow CC, so that the rod contacting arm 1024 contacts the rod 60. Thiscauses the implant 50 and the rod 60 to be drawn together, so as toreduce the rod 60 into the head 52 of the implant 50.

FIGS. 15A-15C are partial perspective and front views showing operationof another embodiment of the rod coercer of the present invention, whichis similar in construction to the rod coercer shown in FIG. 9 and isgenerally indicated at 1100. In this embodiment, a flexible retainer1140 is provided which interconnects the implant gripping arms 1128,1130. The retainer 1140 allows the arms 1128, 1130 to be maintained in afacing relationship with each other as they are pivoted about pivotpoint 1116, as well as when one of the arms 1128, 1130 is moved.

As shown in FIG. 15B, when the arms 1128, 1130 are in a closedarrangement, the retainer 1140 is generally arched. When the arms 1128,1130 are pivoted in the direction of arrow DD, as shown in FIG. 15C, theretainer 1140 flexes while maintaining the arms 1128, 1130 in facingrelationship.

Having thus described the invention in detail, it is to be understoodthat the foregoing description is not intended to limit the spirit orscope thereof. What is desired to be protected is set forth in thefollowing claims.

What is claimed is:
 1. A rod coercer, comprising: first and secondpivotally interconnected handle branches; first and second rodcontacting arms extending from the first and second handle branches andshaped to form surfaces shaped to contact a rod; first and secondimplant gripping arms pivotally interconnected with the first and secondhandle branches; and means for releasably locking the first and secondhandle branches in a fixed position with respect to each other; whereinthe first and second implant gripping arms are fixedly attachable to animplant, the first and second handle branches are pivotable about afirst axis to fixedly clamp the first and second implant gripping armsagainst the implant, and the first and second handle branches arepivotable about a second axis different from the first axis to urge therod and the implant together to reduce the rod into the implant.
 2. Therod coercer of claim 1, wherein the first and second implant grippingarms include cylindrical inner surfaces contacting a head of theimplant, and shoulders abutting the head of the implant.
 3. The rodcoercer of claim 1, wherein each rod contacting arm comprises a curvedsurface.
 4. The rod coercer of claim 1, wherein each handle branchcomprises a finger loop for receiving an operator's finger.
 5. The rodcoercer of claim 1, wherein the means for releasably locking the firstand second handle branches comprises locking tabs.
 6. The rod coercer ofclaim 1, wherein the means for releasably locking the first and secondhandle branches comprises a ratchet assembly.
 7. The rod coercer ofclaim 6, wherein the ratchet assembly further comprises a toothed leverand a pawl.
 8. The rod coercer of claim 1, further comprising a rolleron an end of at least one of the rod contacting arms.
 9. The rod coercerof claim 1, further comprising a flexible retainer interconnecting theimplant gripping arms.
 10. The rod coercer of claim 9, wherein theflexible retainer is generally arched when the implant gripping arms arein a closed arrangement.
 11. The rod coercer of claim 9, wherein theflexible retainer allows the implant gripping arms to maintain a facingrelationship with each other as the implant gripping arms are pivotedaway from each other.
 12. The rod coercer of claim 1, further comprisinga cannula positioned between and engaged with the implant gripping armsto guide a set screw.